U.S. patent number 9,305,395 [Application Number 13/576,178] was granted by the patent office on 2016-04-05 for dental imaging apparatus.
This patent grant is currently assigned to PLANMECA OY. The grantee listed for this patent is Christian De Godzinsky, Juha Koivisto, Kustaa Nyholm. Invention is credited to Christian De Godzinsky, Juha Koivisto, Kustaa Nyholm.
United States Patent |
9,305,395 |
Nyholm , et al. |
April 5, 2016 |
Dental imaging apparatus
Abstract
The invention relates to a dental imaging apparatus which
includes an x-ray imaging means and at least one color camera for
photographing the face of a patient positioned at the imaging
station of the apparatus, which at least one color camera is
arranged to image the patient's face positioned at the patient
support station from different directions, and means arranged into
functional connection with said at least one color camera for
creating a virtual three-dimensional texture model of the patient's
face.
Inventors: |
Nyholm; Kustaa (Siuntio,
FI), De Godzinsky; Christian (Vantaa, FI),
Koivisto; Juha (Helsinki, FI) |
Applicant: |
Name |
City |
State |
Country |
Type |
Nyholm; Kustaa
De Godzinsky; Christian
Koivisto; Juha |
Siuntio
Vantaa
Helsinki |
N/A
N/A
N/A |
FI
FI
FI |
|
|
Assignee: |
PLANMECA OY (Helsinki,
FI)
|
Family
ID: |
44355006 |
Appl.
No.: |
13/576,178 |
Filed: |
February 2, 2011 |
PCT
Filed: |
February 02, 2011 |
PCT No.: |
PCT/FI2011/050090 |
371(c)(1),(2),(4) Date: |
July 31, 2012 |
PCT
Pub. No.: |
WO2011/095694 |
PCT
Pub. Date: |
August 11, 2011 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20120300895 A1 |
Nov 29, 2012 |
|
Foreign Application Priority Data
|
|
|
|
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Feb 2, 2010 [FI] |
|
|
20100036 |
Feb 2, 2010 [FI] |
|
|
20100037 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06T
17/00 (20130101); G06T 17/20 (20130101); A61B
5/1079 (20130101); A61B 6/032 (20130101); A61B
6/4417 (20130101); G06T 15/04 (20130101); A61B
5/0064 (20130101); A61B 6/5247 (20130101); A61B
6/14 (20130101); G06T 2210/41 (20130101); G06T
2215/16 (20130101) |
Current International
Class: |
A61B
6/00 (20060101); A61B 6/14 (20060101); A61B
5/00 (20060101); G06T 17/00 (20060101); A61B
5/107 (20060101); A61B 6/03 (20060101) |
Field of
Search: |
;378/4 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10317137 |
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Nov 2004 |
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DE |
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10315242 |
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Feb 2006 |
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DE |
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2 130 491 |
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Dec 2009 |
|
EP |
|
2006-204330 |
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Aug 2006 |
|
JP |
|
WO 2009/140582 |
|
Nov 2000 |
|
WO |
|
WO 2004/098378 |
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Nov 2004 |
|
WO |
|
WO 2006/071002 |
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Jul 2006 |
|
WO |
|
WO 2008/019355 |
|
Feb 2008 |
|
WO |
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WO 2008/072398 |
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Jun 2008 |
|
WO |
|
Primary Examiner: Johnston; Phillip A
Attorney, Agent or Firm: Fay Sharpe LLP
Claims
The invention claimed is:
1. A dental imaging apparatus, which apparatus includes a support
construction (11, 13) for supporting a structure supporting imaging
means (14), at least one imaging station (18) for placing a patient
to the apparatus for imaging, in which apparatus the imaging means
includes at least an x-ray source (15) and a means for receiving
x-ray image information (21), which have been arranged in the
apparatus in such a way with respect to said imaging station (18)
that the x-ray source (15) and the means for receiving x-ray image
information (21) can be positioned at opposite sides of the imaging
station (18) such that a beam generated by the x-ray source (15)
can be aligned to go through said imaging station (18) and towards
said means for receiving x-ray image information (21), a control
system for controlling operations of the imaging apparatus and a
means integrated with the imaging apparatus or arranged into
functional connection with it for processing information detected
at the receiver of x-ray image information (21), characterized in
that the apparatus includes at least one lighting structure (23) to
illuminate the patient's face positioned at the imaging station
(18) and said control system includes a means for controlling said
lighting structure (23) to produce pulsed white light and/or to
produce light of different colours, the apparatus further including
a means for photographing (22) a patient's face and/or for
producing a moving picture of the patient's face from at least two
directions while the patient is positioned at said imaging station
(18), said means for photographing forming a module with said means
for receiving x-ray image information (21) which means comprises at
least one colour camera (22) the location of which with respect to
said imaging station is arranged changeable and/or at least two
colour cameras being arranged to image the patient's face
positioned at the patient support station (18) from different
directions, and a means arranged into functional connection with
said at least one colour camera (22) for processing the image
information acquired when imaging the patient's face to create a
virtual three-dimensional texture model of the patient's face,
and/or for combining the image information detected by said at
least one colour camera (22), or the three-dimensional texture
model created from it, to a surface model of the patient's face to
create a virtual three-dimensional texture model of the patient's
face.
2. The imaging apparatus according to claim 1, characterized in
that the apparatus includes a means for creating a virtual model
which comprises x-ray image information at least from a portion of
the bones and/or teeth of the patients cranial area integrated with
said virtual three-dimensional texture model produced of the
patients face.
3. The imaging apparatus according to claim 1, characterized in
that the control system of the apparatus comprises a means for
implementing the x-ray imaging and the imaging of the patients face
at the same time and/or as a combined imaging taking place during
one imaging event, and/or the control system of the apparatus
comprises a selection means for implementing the x-ray imaging and
the imaging of the patient's face either with at least one of the
above ways or for implementing at least one of said imagings as a
separate imaging.
4. The imaging apparatus according to claim 1, characterized in
that said at least one lighting structure (23) and/or at least one
colour camera (22) is arranged to the apparatus such that the
patients face can be illuminated and imaged from different
directions when the patient is positioned at said imaging station
(18) arranged for x-ray imaging.
5. The imaging apparatus according to claim 1, characterized in
that said means for illuminating the patients face (23) are
arranged to comprise a lighting structure which directs light
towards the patient's face arranged at the imaging station (18)
substantially from above or from below said at least one colour
camera (22).
6. The imaging apparatus according to claim 1, characterized in
that said means for illuminating the patient's face (23) is
arranged to the substantial proximity of said receiver of x-ray
image information (21) as a component of the module.
7. The imaging apparatus according to claim 1, characterized in
that the apparatus includes at least two colour cameras (22) and
they are arranged to be located horizontally at a distance from
each other.
8. The imaging apparatus according to claim 1, characterized in
that the apparatus includes at least two colour cameras (22) into
connection with which is arranged a lighting structure (23) which
directs light towards the face of the patient positioned at the
imaging station (18) substantially from above and from below of at
least two colour cameras (22), which at least two colour cameras
(22) and the lighting structures (23) arranged into connection with
them are arranged horizontally at a distance from each other on the
opposite sides of said receiver of x-ray image information
(21).
9. The imaging apparatus according to claim 1, characterized in
that said means for illuminating the patient's face (23) and at
least one colour camera (22) are arranged into connection with said
structure supporting the imaging means (14).
10. The imaging apparatus according to claim 9, characterized in
that said structure supporting the imaging means (14) is arranged
rotatable with respect to a vertical virtual axis going through the
patient support station or some other virtual vertical axis.
11. The imaging apparatus according to claim 1, characterized in
that structures, components and control means of the apparatus
related to x-ray imaging are arranged to enable dental panoramic
imaging, dental computed tomography imaging and/or dental cone-beam
computed tomography imaging.
12. The imaging apparatus according to claim 1, characterized in
that said structure supporting the imaging means (14) is arranged
rotatable with respect to the imaging station (18) for at least 180
degrees and the control system of the apparatus to control said at
least one colour camera (22) to shoot at least two colour images of
the patients face positioned at the imaging station (18) within the
angle range in question.
13. The imaging apparatus according to claim 1, characterized in
that information detected by said receiver of x-ray image
information (21) and at least one colour camera (22) is arranged to
be directed to the same one frame grabber, and/or via the same one
Ethernet cable from the imaging device to physically separate means
for processing image information (30).
14. The imaging apparatus according to claim 1, characterized in
that the apparatus includes a means integrated in it or brought to
functional connection with it for creating a three-dimensional
surface model of the patients face.
15. The imaging apparatus according to claim 1, characterized in
that to the apparatus is arranged at least one laser (24) or other
lighting arrangement which is arranged to direct a light pattern on
the patients face positioned at the imaging station (18).
16. The imaging apparatus according to claim 14, characterized in
that said means for creating the surface model of the patients face
includes at least one laser or other light source (24) casting a
narrow vertical light pattern on the patients face positioned at
the imaging station (18), which light source is placed to said
structure supporting the imaging means (14), and that the structure
supporting the imaging means (14) in question and said imaging
station (18) are arranged movable with respect to each other such
that said light pattern can be directed substantially extensively
at different locations within the patient's facial area.
17. The imaging apparatus according to claim 14, characterized in
that the apparatus includes two lasers (24) or corresponding light
sources producing a light pattern arranged substantially on the
same vertical virtual axis, which are arranged to the apparatus
with respect to the imaging station (18) such that the upper of
them illuminates the patients face at least slightly obliquely from
above and the lower at least slightly obliquely from below.
18. The imaging apparatus according to claim 14, characterized in
that to said structure supporting the imaging means (14) is
arranged a receiver module of image information (20) to which is
placed each of the receiver of x-ray image information (21), at
least one colour camera (22), the means for illuminating the face
(23) and the means for producing a laser light pattern (24).
19. The imaging apparatus according to claim 14, characterized in
that said structure supporting the imaging means (14) is arranged
rotatable with respect to the imaging station (18), said light
pattern to move according to the motion of said structure
supporting the imaging means (14) and the control system of the
apparatus to shoot tens or hundreds of images of the light pattern
with said at least one colour camera (22) from different directions
within the area of motion area of the structure supporting the
imaging means (14) in question.
20. The imaging apparatus according to claim 18, characterized in
that seen in the horizontal direction, to the receiver module of
image information (20), substantially in the middle of it, is
arranged the receiver of x-ray image information (21) and two
lasers or corresponding means (24), and substantially at opposite
ends of the module (20) are arranged on the one hand the first and
the second colour camera (22), on the other hand the first and the
second lighting structure (23), and that seen in the vertical
direction, said lasers or corresponding means (24) are arranged to
the receiver module of image information (20) in question
substantially at its edges, and said lighting structures (23) to
direct light at the imaging station (18) from above and from below
said colour cameras (22).
21. The imaging apparatus according to claim 14, characterized in
that the control system of the apparatus comprises a control
routine, controlled by which the structure supporting the imaging
means (14) rotates with respect to the imaging station (18), during
which rotation, the means for illuminating the patients face (23)
are controlled to illuminate the patient's face positioned at the
imaging station (18) in short pulses, preferably at least at the
frequency of 50 Hz, the laser, lasers or corresponding means (24)
are controlled to produce a light pattern on the patients face
otherwise continuously but such that during the rotation of the
structure supporting the imaging means (14), there are moments when
the light pattern is not produced, and the colour camera or cameras
(22) are controlled to shoot images during first steps when the
light pattern is directed on the face and when the means for
illuminating the patients face (23) do not illuminate the face, and
on the other hand during second steps when no light pattern is
directed on the face and when the means for illuminating the
patients face (23) illuminate the face.
22. The imaging apparatus according to claim 21, characterized in
that said structure supporting the imaging means (14) is arranged
to rotate with respect to the imaging station (18) for at least 180
degrees and that according to said control routine, there are short
periods during the rotation in question, such as less than 10
periods, during which no light pattern is directed on the patient's
face and during which the colour camera or cameras (22) are
controlled to shoot images at phases when the means for
illuminating the patients face do produce a light pulse.
23. The imaging apparatus according to claim 1, characterized in
that said receiver means of x-ray image information (21) comprise a
detector, the dimensions of the area receiving image information of
which are at least of the order of centimeters, said structure
supporting the imaging means (14) is arranged to be rotatable with
respect to a vertical, virtual rotation axis going through the
stationary imaging station (18) such that the x-ray source (15) and
the receiver means of x-ray image information (21) move on opposite
sides of the imaging station (18), in which the control system of
the apparatus comprises the control routine, which on the one hand
controls the rotating motion of the structure supporting said
imaging means (14), the x-ray source (51) and the receiver means of
x-ray image information (21) to produce image information, of which
with said means for processing information (30) detected by the
receiver of x-ray image information (21) can reconstruct a
three-dimensional x-ray image, and on the other hand, controls at
least said colour camera (22) to shoot colour images of the
patients face positioned at the imaging station (18) during said
rotating motion, and that the image information processing means
(30) functionally pertaining to the apparatus are arranged to
create a three-dimensional model of the patient positioned at the
imaging station (18) which is presentable on a display (31), which
model shows at least a portion of the bones and/or teeth of the
patient's cranial area and at least a portion of the texture of the
patient's facial area.
24. An apparatus according to claim 1, characterized in that the
apparatus includes a means for producing a green laser or other
light fan and directing it towards the patients face positioned at
the imaging station to create a substantially vertical narrow line
of light on the face.
25. An apparatus according to claim 1, characterized in that the
apparatus includes two lasers (24), the first of which is arranged
to produce laser light of a first colour and the second of a second
colour.
26. An apparatus according to claim 1, characterized in that the
apparatus includes at least two light sources (23) in front of
which is arranged a diffusing foil and/or a polarizer.
Description
FIELD OF INVENTION
The invention relates to a dental imaging apparatus according to
the preamble of claim 1.
BACKGROUND OF INVENTION
The history of medical x-ray imaging originates approximately to
the time of inventing x-radiation. For more advanced ways of
imaging, e.g. the development of panoramic x-ray imaging in the
dental field started for over a half century ago. The development
of digital imaging especially in the 1990s brought digital x-ray
imaging devices also to dental practices. The latest development
step in the dental field has been the generalisation of the
cone-beam computed tomography apparatus designed for
three-dimensional imaging of skeletal structures of the cranial
area. Concerning new possibilities offered by them, worth
mentioning is e.g. applications related to implant attachment and
other treatment planning.
Along with the development of cameras and information technology,
such as that of computing power of computers, it has become
possible to create virtual three-dimensional surface models of
different surfaces. In the dental field, facial surface models can
be utilised e.g. in connection with orthodontic treatment, as
orthodontic treatment can also have an effect on facial shapes.
Such surface models have sometimes been combined with information
on surface texture, i.e. that of details of the surface/surface
structure.
The prior art also includes techniques to create a virtual
three-dimensional texture model without a separately created model
of the three-dimensional shape of the surface.
Among others, the need for acquiring a separate device for a
particular imaging purpose has been limiting utilisation of facial
texture models in the dental field. Acquiring a separate device is
not only a question of costs but also of space, as each device
always requires a space to be installed and/or stored in and/or
where it can be used. On the other hand, each separate imaging
always takes a certain amount of time, too. Furthermore, as far as
data processing is concerned, there are certain challenges in the
arrangements in which creating the model requires combining image
information acquired at different times, image information acquired
by different imaging devices and/or image information acquired of
an anatomy having been positioned in different ways for
imaging.
BRIEF DESCRIPTION OF INVENTION
The object of the invention is a versatile dental imaging
apparatus, by means of which it is possible to create for the
virtual three-dimensional modelling of a patient's skull at least
x-ray image information on the patient's cranial skeletal structure
and, further, information on the colours, scars, hair, moles etc.
of the patient's face. The apparatus according to the invention
includes means for producing not only x-ray images but also
three-dimensional images comprising a facial surface texture.
Preferably, the apparatus is arranged to enable creating 3D images
on the cranial skeletal structure and/or teeth and, with the same
patient positioning and imaging event, information on facial
soft-tissue surface shapes and surface texture. Essential
characteristics of the invention are defined in more detail in the
accompanying patent claims.
The invention introduces a new arrangement for versatile modelling
of the patient's cranial anatomy. The invention enables, among
others, using existing imaging devices and avoiding the need to use
prior-art special arrangements, which lowers the dentists'
threshold to employ the possibilities offered by virtual 3D
models.
Next, the invention and its preferable embodiments will be
described in more detail also with reference to the enclosed
figures.
BRIEF DESCRIPTION OF FIGURES
FIG. 1 shows one imaging apparatus according to the invention, the
basic structure of which includes a base construction and an arm
part supporting imaging means.
FIG. 2 shows a receiver module of image information applicable for
use in the apparatus according to FIG. 1.
FIG. 3 shows directing of laser beams from the module according to
FIG. 2 towards a patient positioned at an imaging station.
FIGS. 4a and 4b show signal paths according to one preferable
embodiment of the invention from an x-ray detector and at least one
colour camera via a frame grabber to a computer.
FIGS. 5a-5c show examples on various virtual three-dimensional
facial models.
FIG. 6 shows a principle according to one preferable embodiment of
the invention for controlling certain operations of the
apparatus.
DETAILED DESCRIPTION OF INVENTION
FIG. 1 shows one imaging apparatus according to the invention. The
apparatus includes a vertical support construction (11) from which
horizontally extends an arm (12) supporting a patient support means
and an arm part (13) which supports a structure supporting imaging
means of the apparatus, an arm part (14). The arm part supporting
the imaging means (14) may be arranged rotatable. To the arm part
supporting the imaging means (14) are arranged at a distance from
each other an x-ray source (15) and a receiver of x-ray image
information (21), which are located at the apparatus with respect
to a patient support means (17) such that an imaging station (18)
is created to the apparatus which is located between the x-ray
source (15) and the receiver means of x-ray image information (21)
such that a beam produced by the x-ray source (15) can be directed
to go through said imaging station (18) towards the receiver means
of x-ray image information (21). The apparatus includes control
means, of which FIG. 1 shows a control panel (16) arranged to the
support construction (11) and operating mode selection means (19)
pertaining in it. In the apparatus according to FIG. 1, the
receiver means of x-ray image information (21) are arranged as part
of a receiver module of image information (20) which is arranged
into connection with a computer (30) via a cable. A means for
processing image information is arranged to the computer, and a
display (31) to present images created by the computer.
FIG. 2 shows a receiver module of image information (20) applicable
for use in the apparatus according to FIG. 1. The module includes
two colour cameras (22) arranged horizontally on opposite sides of
the x-ray detector (21) and aligned at the imaging station (18).
Further, light sources (23) preferably producing white light to
illuminate the imaging station (18) and two lasers (24) are
arranged to the module (20). These lasers are positioned
substantially in the middle of the module (20) to the substantial
proximity of its upper and lower edges. The lasers (24) are
arranged to emit and direct at the imaging station (18) a narrow
vertical planar fan beam which casts a laser light pattern on the
patient's face. FIG. 3 shows how the laser fan beams produced by
the two lasers (24) shown in FIG. 2 can be directed at the imaging
station (18) to cover the patient's face in the vertical direction
without shadow areas.
The invention can employ two lasers (24) of the same colour or they
may be of different colour, the first can be arranged to produce
laser light of a first and the other of a second colour. When using
lasers of the same colour, it can be challenging to implement the
structure in practice such that the lasers (24) produce exactly
overlapping beams. This can already be difficult from the viewpoint
of manufacturing techniques and, further, alignment problems may
also occur later on when using the device. As regards to lasers of
different colours, they can be arranged to point at different
directions and can be identified in the image e.g. by machine
vision based on searching the image for the hues in question. If
the mutual alignment of the lasers of different colours changes
during use, instead of realigning the lasers (which could require
service at the factory), it is possible to fix the situation by
recalibration.
The light sources (23) arranged to the apparatus can be arranged to
produce lights of other colour or colours than white, too.
Diffusing foils may be arranged in front of the light sources (23)
(cf. surface (23) in FIG. 2), whereby light is emitted from a
larger area and substantially evenly and illumination in the target
area will be even. Furthermore, the light sources (23) may be
provided with polarizers (cf. surface (23) in FIG. 2) which can
eliminate mirror reflection from the skin surface possibly
otherwise visible in the image of the second camera, caused by the
light source located in connection with the first camera, and vice
versa. It is also possible to arrange to the apparatus more than
two or only one colour camera (22), and the cameras or camera (22)
can be arranged to operate not only as a photographic camera but
also as a continuously-operating video camera. The light pattern to
be directed on the patient's face can be produced by some other
light source than a laser and the colour of this light pattern,
too, can be arranged changeable and, even when produced by a laser,
its colour can be some other than the conventional red, such as
preferably particularly green.
When the structure supporting the imaging means (14) of the
apparatus according to FIG. 1 is arranged rotatable, it is possible
for the one or more colour cameras (22) arranged to the receiver
module of image information (20) to shoot images from the patient's
face positioned at the imaging station (18) from different
directions. Then, it is also possible to make the laser light
pattern to scan the patient's face. When using e.g. the arrangement
according to FIG. 2, in which the camera (22) and the laser (24)
are positioned at a distance from each other, it is possible to
scan the patient's face positioned at the imaging station (18) with
the laser line and, at the same time, to shoot images of the face
at an angle (at an angle of less than 90 degrees) with respect to
the direction of the laser beam. Of the image information acquired
this way, it is possible to produce a three-dimensional surface
model of the patient's facial shape. In one preferable embodiment
of the invention, the control system of the apparatus is provided
with a control function to always momentarily switch off the laser
for a desired duration during a scan, during which periods it is
possible to shoot colour images of the patient's face without the
laser light pattern and to produce from the hence acquired image
information a texture model of the patient's face. However, it is
in principle possible to operate also such that the laser is not
switched off at all but the laser line is removed from the texture
model being formed during processing of the image information
produced in the imaging programmatically.
FIG. 4a shows a signal path from the receiver module of image
information (20) to the computer (30) used in one preferable
embodiment of the invention. The signal path of image information
detected by the colour camera or cameras (22) and the x-ray
detector (21) to the computer (30) can be arranged shared such that
the image information acquired from them is directed to the
computer (30) via the same one frame grabber. Preferably, a signal
path is also arranged in the apparatus at least between the control
means of the movements of the imaging means and/or the control
means of the x-ray source and the computer via the same Ethernet
cable as the signal path from the camera to the computer. This can
be implemented e.g. by means of an Ethernet-HUB component or an
Ethernet switch component arrangeable to the apparatus. FIG. 4b
shows another preferable embodiment for arranging signal paths to
the apparatus which also requires only one Ethernet cable between
the imaging means and the computer.
The means arranged to the computer (30) to process image
information acquired when imaging the patient's face arranged at
the imaging station (18) comprise, according to the invention, an
algorithm for processing at least image information acquired from
the x-ray detector (21) and for processing image information
acquired from the colour camera or cameras (22) to create a virtual
three-dimensional texture model of the patient's face. The texture
model can be produced either solely of the photography information
picturing the patient's face from more than one direction, or its
production can utilise e.g. information on the shape of the surface
of the soft-tissue of the patient's face acquired when x-ray
imaging the patient. In a preferable embodiment of the invention,
the image processing means includes a means for creating a facial
surface model from the image information of the laser line directed
on the patient's face, which information can be utilised in
producing the three-dimensional texture model of the patient's
face. Preferably, the image processing means includes a means which
can produce models which simultaneously show three-dimensionally
both the facial texture and at least parts of the teeth and/or
skeletal structure of the patient's cranial area.
FIG. 5a shows an example of a facial three-dimensional model
implementable with the apparatus according to the invention in
which to the facial texture model is integrated information on the
skeletal structure and teeth of the cranial area of the patient.
FIG. 5b again shows an example of a facial surface model
produceable with the above-described apparatus according to the
invention, and FIG. 5c a different projection of the model
according to FIG. 5b, which is produced only of information
acquirable from the laser line patterns on the patient's face.
Comparing FIGS. 5b and 5c illustrates how the facial texture model
produceable with the apparatus according to the invention differs
from a mere facial surface model.
FIG. 6 shows a diagram which illustrates a principle according to
which certain operations of the apparatus according to the
above-described embodiment can be controlled. In the figure, the
imaging of the patient's face is assumed to be
implemented--simultaneously with x-ray exposure or as its own
imaging--such that the arm part supporting the imaging means (14)
is made to rotate such that the receiver module of image
information (20) moves from one side of the patient's face to the
other for at least 180 degrees, such as for at least 200 degrees,
such as for about 260 degrees. During this motion, the patient's
face is illuminated by regularly pulsing the light sources (23) of
the receiver module of image information (20), whereas the laser
light is otherwise kept continuously on but, during the scan, it is
momentarily switched off in order to be able to shoot images from
the face of the patient positioned at the imaging station (18) also
without the laser light pattern. The operations of the apparatus
are synchronised to comprise two kinds of periods, during the first
of which the laser light is switched off and images are shot of the
face during such sequences of the light pulses whereby the
patient's face is illuminated, and during the second periods the
laser light is again kept on whereby the laser line, when the arm
part supporting the imaging means (14) rotates, moves along the
patient's face and images are shot of the face during such periods
of the light pulses whereby the patient's face is not illuminated.
When the imaging employs two colour cameras (22) according to the
embodiment of the invention described above, concerning the
operation mode shown in FIG. 6, the control as described above is
implemented such that the first and the second camera (22) shoot
images always during successive light pulses. The image information
integrated by the cameras (22) can be read out always during those
periods of the light pulsing when image information is not being
integrated.
The diagram of FIG. 6 thus shows one principle applicable for use
in the invention. However, if desiring to prevent the patient
positioned at the imaging station from sensing the flickering of
lights caused by the pulsing of facial illumination, the pulse
frequency of the illumination must be arranged to be at least 50-60
Hz. Such pulsing would lead, when operating exactly the way shown
in FIG. 6, to an unnecessarily large amount of image information
for practical implementation of the invention. The above principle
can indeed be applied e.g. such that, during the above-described
periods, the first and the second camera do not shoot images during
each light pulse but only e.g. at times of the order of every tenth
pulse, whereby there also is more time for reading the image
information from the camera. Thus, in one preferable embodiment of
the invention, the means for illuminating the patient's face is
controlled to illuminate the patient's face in short pulses,
preferably at least at the frequency of 50-60 Hz, the laser or
lasers are controlled to produce a laser light pattern on the
patient's face otherwise continuously but such that there are
periods during the rotation of the arm part, such as less than 10
periods, during which no laser light pattern is produced, and the
colour camera or cameras are controlled to shoot images at the
first pulse steps when the laser light pattern is directed on the
face and when the means for illuminating the patient's face do not
illuminate the face, and at the second pulse steps whereby no laser
light pattern is directed on the face and when the means for
illuminating the patient's face do illuminate the face. One
practical way to implement sequencing of shooting images according
to the practical mode of operation described above comprises
implementing the first and the last period during movement of the
imaging means as periods during which the face is imaged without a
laser line and for the duration of the movement in question, this
kind of periods are arranged for the total of five at even
intervals. According to such an embodiment of the invention, for
the total of ten colour images of the patient's face would thus be
shot from different directions without the laser light pattern, and
the angular velocity of the motion of the imaging means from one
side of the patient's face to the other can be arranged such that
during the four periods falling between these periods, images of
the order of 300 are shot of the laser light line directed on the
face. It is still evident to those skilled in the art that it is
e.g. not necessary to shoot images of the laser light pattern at
even intervals and that their number, and the positions from which
images of the laser line are shot, may be varied e.g. according to
the desired horizontal resolution of the surface construction. It
is also not necessary to shoot photographs without the laser line
at even intervals and their number and position can be varied
according to any particular need as well so that suitable joining
points and adequate coverage are achieved for creating a
three-dimensional texture model from the partial facial images shot
from different directions.
The apparatus according to the invention and its operation mode
selection switch (19) can be arranged to enable x-ray imaging and
imaging of the patient's face to occur either separately or, in one
preferable embodiment of the invention, to be implemented in
connection with the same imaging event, even simultaneously.
Photographing the face from different directions simultaneously
with the x-ray imaging eliminates a need for a separate imaging
whereby, among other things, there is no need to calibrate some
other imaging device and to position the patient to this other
device for a separate facial imaging. Thus, trouble and time are
saved when the facial imaging can be performed simultaneously with
the x-ray imaging. Also, if one wishes to integrate image
information acquired in different ways of imaging, e.g. to be
presented in the same three-dimensional model, the combining is
then easier as the imaged anatomy has been in the same position and
in the set of coordinates according to the same imaging device when
imaged. The apparatus enables the use of the laser line to enhance
bringing out the facial shapes in more detail by transferring the
location of the laser line on the face, by shooting profiles
produced by the laser line on the facial surface and by calculating
the shape of the facial surface from these profiles.
Above, the invention has been described predominantly with
reference to the enclosed figures, but all of the above-described
details of the embodiments of the invention are not necessary or
the only ones possible considering implementing the invention. The
number of colour cameras used in the apparatus can be some other
than two and, if the apparatus enables changing the camera location
with respect to the imaging station, it is possible to shoot images
of the patient's face from different directions even with one
camera. In a preferable embodiment of the invention, the apparatus
is arranged with a lighting arrangement emitting white light to
illuminate the patient's face, which is advantageous considering
imaging the facial hues, but it is possible to consider the
invention being also utilisable without one or several sources of
white light integrated in the apparatus and also with lights of
other colours. Furthermore, adequate information for producing a
three-dimensional facial texture model can be acquired only from
photographing the face from different directions, but the
preferable embodiments of the invention also utilise e.g.
information on the shapes of the facial soft-tissue surface
acquired from an x-ray imaging, or information on the facial
surface shapes available from a laser scan of the face.
The receiver module of image information applicable for use in the
apparatus can according to the embodiment of above comprise the
receiver of x-ray image information (21) arranged substantially in
the middle of the module, seen from the horizontal direction, and
two lasers (24), and arranged substantially at opposite ends of the
module (20) on the one hand a first and a second colour camera
(22), on the other hand a first and a second lighting structure
(23). When viewing the module (20) in the vertical direction, it
may comprise an arrangement in which said lasers (24) are arranged
substantially at the edges of the receiver module of image
information (20), and said lighting structures (23) to direct light
at the imaging station (18) from above and from below said colour
cameras (22). The functionality according to the invention for
modelling at least part of the face can nevertheless be considered
to be achieved with other kinds of arrangements as well, such as
with an arrangement which uses two light lines and only one
camera.
The colour camera pertaining to the apparatus according to the
invention can also be used for other purposes than those described
above. The camera or cameras can be arranged to operate as a video
camera, whereby it is possible to e.g. monitor and/or save the
patient's expressions and possible movements before the x-ray
imaging and/or during exposure, with suitable arrangements also in
3D. In the above embodiments, the colour camera or cameras are
located to the arm part supporting the imaging means to the
substantial proximity of the x-ray detector, but the colour camera
or cameras can also be arranged e.g. to the substantial proximity
of the x-ray source. Generally, it is advantageous to position the
colour camera or cameras, as well as the laser or lasers possibly
pertaining to the apparatus, to such structure of the apparatus
which is already arranged movable with respect to the imaging
station for the purposes of x-ray imaging by the apparatus.
The computer pertaining to the apparatus does not have to be a
physically separate device from the imaging means but it can also
be integrated as part of the actual imaging device.
The x-ray imaging means of the apparatus preferably enable computed
tomography imaging, especially cone-beam computed tomography
imaging known to be used in the dental field, the paths of the arm
part supporting the x-ray imaging means used in which apparatus are
typically arranged to enable rotation of the arm part with respect
to a stationary, virtual vertical axis going through the imaging
station, which motion is also directly utilisable for producing
image information for creating a three-dimensional facial texture
model. This property of the imaging apparatus makes implementation
of especially the facial laser scanning quite simple, as the x-ray
imaging apparatus already includes means to implement movements
applicable for use in laser scanning. The laser scanning can in
many cases significantly facilitate detection of three-dimensional
surface shapes of the patient's face as compared to using
information acquired solely from colour photography of the face. In
a preferable embodiment of the invention, there is then e.g. an
arrangement in which said receiver means of x-ray image information
(21) comprise a detector, the dimensions of the area receiving
image information of which are at least of the order of
centimeters, said structure supporting the imaging means (14) being
arranged to be rotatable with respect to a vertical, virtual
rotation axis going through a stationary imaging station (18) such
that the x-ray source (15) and the receiver means of x-ray image
information (21) move on opposite sides of the imaging station
(18), in which the control system of the apparatus comprises a
control routine, which on the one hand controls the rotating motion
of the structure supporting said imaging means (14), the x-ray
source (15) and the receiver means of x-ray image information (21)
to produce image information, of which with said means for
processing information (30) detected by the receiver of x-ray image
information (21) can be reconstructed a three-dimensional x-ray
image, and on the other hand, controls at least said colour camera
(22) to shoot colour images of the face of a patient positioned at
the imaging station (18) during said rotating motion, and in which
the image information processing means (30) functionally pertaining
to the apparatus are arranged to create a three-dimensional model
presentable on the display (31) of the patient positioned at the
imaging station (18), which model shows at least a portion of the
skeletal construction and/or teeth of the patient's cranial area
and at least a portion of the texture of the patient's facial
area.
According to one preferable embodiment of the invention, the
apparatus includes a means for realizing the imaging such that the
computed tomography imaging is implemented with a rotation angle of
About 200 degrees and the photography with a rotation angle of
about 260 degrees. In practice, this can be then implemented such
that one manoeuvre of 260 degrees is made, during which the x-ray
imaging is started after a movement of 30 degrees and
correspondingly stopped earlier than the photography, or by first
picking up x-ray image information during a manoeuvre of about 200
degrees in a first direction, continuing the movement in this first
direction to the starting position of photography, and implementing
photography during a manoeuvre of 260 degrees occurring in the
opposite direction. An advantage of the latter alternative is that
the motion during mere photography can be implemented as fast (i.e.
with higher angular velocity than the x-ray imaging) without the
velocity needed in computed tomography imaging limiting the angular
velocity, which decreases the risk of the patient's expression
changing or of other motions during exposure.
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